JPH0326395A - Septic tank capable of adjusting reflux amount from aerobic treating chamber to anaerobic treating chamber - Google Patents

Abstract

PURPOSE:To constantly optimize the capacity of a septic tank by refluxing a part of treated water in an aerobic treating chamber and finely adjusting the reflux amt. with a pump controlled by an inverter. CONSTITUTION:A pump driver M2 for a partial reflux pump P is controlled by an inverter 60 to finely adjust the amt. of aerobically treated water to be refluxed to an anaerobic treating chamber C from an aerobic treating chamber a3, and the capacity of the septic tank A is constantly optimized irrespective of the fluctuations in the temp. of treated water in the septic tank main body (a), temp. of the atmosphere (air temp.) around the main body (a) and input load (quantity and quality) to the main body (a). Namely, when the temps. of the air and water are lowered, the reflux amt. is decreased. Furthermore, when the ammonia ion concn. in the aerobic treating chamber a3 is increased, the reflux amt. is decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a septic tank capable of adjusting the amount of return from an aerobic treatment chamber to an anaerobic treatment chamber.

(b) Conventional technology Traditionally, as a form of septic tank, Utility Model No. 63-45894
There are items listed in the issue.

That is, as shown in FIG. 6, the septic tank has a first anaerobic treatment chamber 91 into which sewage flows into the septic tank main body 90, and a first anaerobic treatment chamber 91 into which the sewage treated anaerobically in the first anaerobic treatment chamber 91 flows into the septic tank main body 90. an aerobic treatment chamber 9 into which wastewater further anaerobically treated in the second anaerobic treatment chamber 92 flows.
3, a sedimentation separation chamber 94 into which the wastewater aerobically treated in the aerobic treatment chamber 93 flows, and a disinfection chamber 95 into which the supernatant liquid separated in the sedimentation separation chamber 94 flows.

Further, aerobic treatment in the aerobic treatment chamber 93 is performed by blowing air into the aerobic filter bed 96 from an aeration device 97.

According to this septic tank, the first anaerobic treatment chamber 91
It is considered that anaerobic treatment can be performed in two stages in the first and second anaerobic treatment chambers 92, and then aerobic treatment can be performed to obtain clean treated water.

In addition, as a form of septic tank, the present applicant previously filed a patent application in 1983.
There is one disclosed in No. 2-214009.

Furthermore, the septic tank can adjust the pH of the anaerobic treatment room without using auxiliary materials for PLL adjustment by returning a portion of the acidic aerobic treated water to the alkaline anaerobic decomposition treated water. can.

(c) Problems to be Solved by the Invention However, such septic tanks still have the following problems to be solved.

That is, the applicant conducted research on the relationship between the purification ability of household or personal septic tanks and various environmental factors related to septic tanks.

As a result of this research, the temperature of the treated water in the septic tank,
It was discovered that the amount of dissolved oxygen, ammonia ion, etc. in the treated water fluctuates considerably depending on the ambient temperature around the septic tank and the load (quantity and quality) flowing into the septic tank, and that these fluctuations also cause considerable fluctuations in the purification capacity. .

However, the conventional septic tank described above is designed to constantly supply a fixed amount of aerobically treated water from the aerobic treatment chamber to the anaerobic treatment chamber, despite fluctuations in the environmental conditions of the septic tank. However, it was not possible to effectively adjust the pn in the anaerobic treatment chamber, and it was not possible to effectively deal with the decrease in purification ability.

SUMMARY OF THE INVENTION An object of the present invention is to provide a septic tank structure that can constantly maintain the purifying capacity of a septic tank in an optimal state in accordance with various environmental conditions related to the septic tank.

(2) Means for Solving the Problems The present invention includes arranging an anaerobic treatment chamber and an aerobic treatment chamber in parallel within the septic tank main body, and arranging an aeration device in the aerobic treatment chamber. A part of the treated water in the aerobic treatment chamber can be recirculated, and the amount of the aerobic treated water can be finely adjusted by using a partial recirculation pump controlled by an inverter. This relates to a septic tank that can adjust the flow rate from the aerobic treatment chamber to the anaerobic treatment chamber.

Furthermore, the present invention provides a septic tank structure that allows fine adjustment of the partial return amount of aerobic treated water according to changes in the temperature of the treated water in the septic tank, the ambient temperature around the septic tank, and the inflow load to the septic tank. It also has certain characteristics.

(e) Examples Hereinafter, the present invention will be specifically explained based on the examples shown in the attached paper.

In Figures 1 and 2, A indicates a household septic tank, and the septic tank A consists of a septic tank body a and a lid body b, and is used to discharge sewage from household toilets, kitchens, etc. It is installed in the middle of the pipeline.

As shown in FIGS. 1 to 3, the septic tank main body a has a box-like shape with an open top.

By erecting partition walls 1, 2.3 at regular intervals in the longitudinal direction, the internal space is divided into a first chamber a1 and a second chamber a2, which form the anaerobic treatment chamber C. It is divided into an aerobic treatment chamber a3 and a sedimentation separation chamber a4 in which a disinfection chamber l8 is provided.

Below, the structure of each room will be explained in order, starting with the structure of anaerobic treatment room C. As shown in Figure 1, anaerobic treatment room C
The first chamber a1 communicates with the downstream side of the sewage discharge pipe D via an inlet 4 having a substantially horizontal cross-section shape, and the sewage (hereinafter referred to as "Treated water"
) can be allowed to flow in while being bent downward.

In addition, as shown in FIG. 1, the 1st chamber a of the anaerobic treatment chamber C
1, a downward flow anaerobic filter bed 5 is disposed in the center at a predetermined distance downward from the inlet 4.

The upward flow anaerobic filter bed 9 has substantially the same structure as the above-described downward flow anaerobic filter bed 5, but has a smaller porosity between the filter media and a larger surface area. a1
This is different from the downward flow anaerobic filter bed 5 disposed inside the filter.

Next, to explain the treated water transfer structure for transferring the treated water from the above-mentioned chamber I to the second chamber a, as shown in FIG. 1 and FIG. , completely partitions the area below the treated water level h in the septic tank main body a, and the advection of treated water from the first chamber a to the second chamber a2 is carried out through the first chamber of the partition wall 1. First and second advection pipes 10 are installed upright along the a1 side and the side surfaces of the second chamber 82, respectively.
It will be held throughout the 11th.

The first and second advection tubes 10.11 are in the form of tube bodies whose upper and lower ends are open above and below each filter bed 5, 9, respectively.

The inflowing treated water 1 then flows upward through the upward flow anaerobic filter bed 9 to be subjected to the second anaerobic treatment, and then flows into the aerobic treatment chamber 83 described below. I will do it.

First, with reference to FIG. 1, the second chamber a2 of the anaerobic treatment chamber C
To explain the structure for transferring treated water from the second chamber a2 to the aerobic treatment chamber a3, there is a partition wall 2 between the second chamber a2 and the aerobic treatment chamber a.
completely partitions the area below the treated water level h of the septic tank body a, and advection of the treated water from the second chamber a2 to the aerobic treatment chamber a3 is provided on the side of the partition wall 2 on the side facing the second chamber. This is done by the third advection pipe 16.

Next, the internal structure of the aerobic treatment chamber a will be explained with reference to FIG. 1, FIG. 3, and FIG. 4.

As shown in FIG. 1, the aerobic treatment chamber a3 includes an aerobic filter bed 12, an aeration device l3, and a vertical reflux pipe l4.
and a backwash pipe 15 are built in.

(The vertical reflux pipe 14 is a part of the partially treated water reflux structure E described later, so it will be explained in the explanation of the structure E.) First, regarding the aerobic filter bed 12. To explain, the aerobic filter bed 12 is for performing aerobic treatment in cooperation with the aeration device l3, and in this embodiment, as shown in FIG.
A large number of string-like filter media 12b formed by attaching a large number of fibrous filter threads in a substantially tuft-like shape to a central string are supported on the frame 12a deposited at a predetermined interval from the inner bottom surface in the aerobic treatment chamber a3,
This is achieved by attaching aerobic bacteria to the string-like filter medium 12b.

Next, the aeration device 13 will be explained with reference to FIGS. 1 and 4. From the lower end of the vertical air pipe 13a vertically installed along the partition wall 2 between the second chamber a2 and the aerobic treatment chamber a3, A pair of air diffusers 1 are installed along the bottom of the septic tank body a in the left and right width direction.
3b, 13b are extended, and each diffuser pipe 13b, 1
3b is a fully porous tube provided with a large number of air ejection holes 13d.

With this structure, the vertical air pipe 13a and the air diffuser pipe 13b
．． Air can be diffused into the aerobic treatment chamber a through 13b, and the activity of aerobic bacteria can be maintained.

In addition, as shown in Fig. 4, one end is connected to the air compressor 7.
A diffuser pipe 13 is located in the middle of the air pipe 13c connected to
An aeration amount IIm control valve 50 consisting of a manual flow rate adjustment valve for adjusting the aeration amount of air supplied to b and the air flow are switched to supply air from the aeration pipe 13b to the backwash pipe 15 to be described later. A three-way ball valve 55 is provided.

In this embodiment, the aeration amount control valve 50 is driven by a valve drive device M8 such as an induction motor, and the valve drive device M1 is controlled by an inverter 52.

Next, explaining the backwash pipe 15, the backwash pipe 15 is used to periodically remove excess sludge adhering to the string-like filter medium 12b in the aerobic filter bed 12 and to maintain the activity of aerobic bacteria. belongs to.

As shown in FIGS. 1 and 4, the backwash pipe 15 includes a vertical backwash pipe 15b vertically installed along the partition wall 3 between the aerobic treatment chamber a3 and the sedimentation separation chamber a4, and at the lower end thereof, One end of the air jet pipe 15a arranged substantially horizontally below the aerobic filter bed 12 is connected to the other end, while the upper end of the above-mentioned backwash vertical pipe 15b is connected to the
This is achieved by supporting and communicating with the air pipe 13c in a cantilevered manner via a flexible vibrator 15c.

Then, operate the three-way ball valve 55 to remove the backwash pipe 15.
By blowing out air from the jet pipe 15a and manually swinging the jet pipe 15a via the flexible pipe 15c, the excess sludge can be reliably washed away.

Next, a treated water partial reflux structure for refluxing a portion of the treated water in the aerobic treatment chamber a3 to the first chamber a1 of the anaerobic treatment chamber C will be described.

As shown in FIG. 1, the aerobic treatment chamber a has a vertical reflux pipe 14 disposed vertically along the partition wall 2. As shown in FIG.

As shown in FIG. 1, this vertical reflux pipe l4 has its lower end opened into the aerobic treatment chamber a3, and its upper end is disposed slightly above the treated water surface h, with a part of the reflux pump It is connected to P.

A pump drive device M2 is connected to the pump P, and the pump drive device array 2 is controlled by an inverter 60.

On the other hand, the partial reflux pump P is connected in communication with one end of the return pipe 14b passing through the partition wall 2.
The other end is connected to the first chamber a. At the same time, the tip of the other end is bent downward to open below the treated water surface h.

With this configuration, by driving the pump P for partial reflux, a part of the treated water in the aerobic treatment chamber a3 can be refluxed to the first chamber a1 of the anaerobic treatment chamber C.

In addition, as shown in FIG. 1, in the middle part of the return vibrator 14b located above the second chamber a2, there is a notch opening 14f for cleaning the inside of the pipe, and a cutout opening 14f for measuring the amount of return treated water. A recovery section 40 is provided in each case.

In the construction of the septic tank A, the present invention further provides that the pump drive unit WM2 of the pump P for partial return is connected to the inverter 60.
By controlling the temperature of the treated water in the septic tank body a and the surroundings of the septic tank body a by finely adjusting the flow rate of a part of the aerobic treated water from the aerobic treatment chamber a to the anaerobic treatment chamber C, The system is characterized by a structure that allows the purification capacity of the septic tank A to be constantly maintained at an optimal state regardless of fluctuations in the ambient temperature (air temperature) or the inflow load (quantity, quality) into the septic tank body A. have

FIG. 5 shows a control circuit for the septic tank A that enables inverter control of the pump driving device M2 of the partial reflux pump P described above.

That is, in FIG. 5, an inverter 60 connected to a pump drive device h consisting of an induction motor is connected to a control device 79.

That is, the inverter 52 of the valve drive device M1 and the inverter 60 for controlling the pump drive device M2 are connected to the output interface of the control device W79, and on the other hand, the input interface of the control device 79 is connected to the inverter 52 for controlling the pump drive device M2. Various environmental condition detection sensors such as the atmospheric temperature sensor 80 installed in the septic tank body a, the water temperature sensor 81 installed in the septic tank body a, the nitric acid/nitrite ion sensor 84, the ammonia ion sensor 85, 86, and the pI sensor 87, 88 are connected. has been done.

Based on the detection outputs from the various environmental condition detection sensors mentioned above, the pump driving device H2 of the pump P for partial circulation is controlled by the inverter 60, thereby steplessly changing the rotation speed of the pump driving device. , the reflux amount of aerobic treated water can be automatically fine-tuned.

Note that known devices and methods can be used to measure the values of the above environmental conditions. For example, in the measurement of ammonia ions, a potentiometer, an ion electrode, a reference electrode, a sample container, a magnetic stirrer, and a temperature needle are used. An ion electrode method device constructed from the above can be used, and for pn measurement, one described in JIS Z 111802 can be used.

In this example, we focused on the environmental conditions shown in the table below,
The partial return amount of the aerobic treated water from the aerobic treatment chambers a and anaerobic treatment chamber C will be finely adjusted.

In the table above, "change" refers to a change in each environmental condition listed in the "Environmental conditions"section; ↑ indicates that each value has increased, and ↓ indicates that each value has decreased. show.

Further, in the environmental conditions, (favorable) indicates the aerobic treatment chamber a3, and (unfavorable) indicates the anaerobic treatment chamber C.

On the other hand, ↑ and ↓ in “treated water return amount” are respectively
Indicates the method to be taken when environmental conditions change as shown in the table.

That is, when the air temperature or water temperature decreases, an operation is performed to partially reduce the amount of recirculation of the aerobically treated water. In addition, aerobic treatment room a
If the ammonia ion concentration at , increases,
Perform an operation to partially reduce the amount of reflux of aerobically treated water.

Thereby, the purification capacity of the septic tank A can be maintained at an optimal state at all times.

Hereinafter, a method for purifying wastewater from a household toilet or kitchen using a septic tank having the above-mentioned structure will be described with reference to FIG.

From the upstream side of the sewage discharge pipe D through the inlet 4, the first chamber a
The treated water flowing into 1 and the organic substances contained in the treated water (water, carbohydrates, proteins, lipids, urea, etc.) pass through the downward flow anaerobic filter bed 5. It undergoes anaerobic decomposition by anaerobic bacteria attached to the surface of the filter medium of the filter bed 5.

That is, first, the organic matter in the treated water is reduced to a low molecular weight by acidogenic bacteria, and is converted into acetic acid (CII3COOl+) and propionic acid.
C}13cHZcOOI+), etc., and then the organic acid is decomposed by anaerobic bacteria such as methane bacteria.
By producing methane (CH.) and carbon dioxide (CO■),
These gases are released outside the septic tank A, and ammonia nitrogen (N
ll. ”-N).

Incidentally, coarse solids contained in the treated water that has passed through the downward flow anaerobic filter bed 5 settle at the bottom of the first chamber al.

By performing such anaerobic treatment, organic matter can be effectively removed from the treated water, and as a result, the treated water after anaerobic treatment contains ammonia nitrogen (NH4
-N) and a small amount of untreated organic matter in the first chamber a.
1 to the second chamber a2.

That is, the treated water after the anaerobic treatment passes through the first advection pipe 10 and the second advection pipe 11, and is placed below the upward flow anaerobic filter bed 9 in the second chamber a2 by the filter bed 9. Directly transported without anaerobic treatment.

Thereafter, while passing through the upward flow anaerobic filter bed 9 from bottom to top 15 16 , the same anaerobic decomposition as described above occurs again, and organic matter is further decomposed, and then ammonia nitrogen (NH. The treated water containing a further small amount of untreated organic matter is transferred to the next aerobic treatment chamber a through the third advection pipe I6.

Therefore, in this embodiment, the second chamber a2 of the anaerobic treatment chamber C
The treated water is subjected to anaerobic treatment in an upflow anaerobic filter bed 9.
By creating an upward flow that passes through the anaerobic filter bed from the bottom to the top, the flow rate can be made slower than when creating a downward flow that passes through the anaerobic filter bed from the top to the bottom. More undecomposed substances can be anchored in the filter bed, and anaerobic decomposition can be further promoted.

Therefore, in addition to the anaerobic treatment in the first chamber a1, the anaerobic treatment in the entire anaerobic treatment chamber C can be performed efficiently and sufficiently to reduce the generation or residual of undecomposed organic matter as much as possible. In addition, acidogenic bacteria and anaerobic bacteria in the above anaerobic treatment are
Although it is possible to wait for the growth of acidophilus bacteria and anaerobic bacteria that have entered the treated water from the environment and then use them, it is preferable to inoculate with a good starter strain that has a proven track record.

In addition, the treated water that has been anaerobically treated in the first chamber al of the anaerobic treatment chamber C is directly sent to the bottom of the second chamber a2, and
! Since the undecomposed substances are not sent to the upper part of the upflow anaerobic filter bed 9, undecomposed substances may remain in the upper part of the upflow anaerobic filter bed 9, or the undecomposed substances may be transferred from the second chamber a2 to the second chamber a2.
It is possible to reliably prevent the water from flowing directly into the aerobic treatment chamber a, which is arranged in parallel with the aerobic treatment chamber a.

Next, to explain the purification process in the aerobic treatment room a3, air is blown into the treated water from the aeration pipe 13b of the aeration device l3, and the oxygen in the air is used. Oxidative decomposition by aerobic bacteria such as nitrifying bacteria causes ammonia nitrogen (NI1
4N) is oxidized and decomposed into nitrate nitrogen (NOs-N) and nitrite nitrogen (NO!--N).

As for aerobic bacteria, it is preferable to inoculate with proven seed bacteria as mentioned above, and by attaching such aerobic bacteria to the aerobic filter bed 12, the bacteria concentration will decrease due to outflow of aerobic bacteria. Don't you have anything to do? I have to.

Furthermore, in this example, all of the treated water that has been subjected to the anaerobic treatment and aerobic treatment is not discharged as it is outside the septic tank A, but the treated water that is undergoing aerobic decomposition in the aerobic treatment chamber a. A part of the reflux pump P is driven, and a part of
I am planning to send it back to .

Therefore, when treated water containing nitrate nitrogen (NOa-N) and nitrite nitrogen (NOx--N) flows into the first chamber a, the denitrifying bacteria present in the first chamber a1 Using oxygen from an inorganic compound, the first chamber a. It decomposes organic matter that flows into the body to obtain energy for survival.

As a result, inorganic compounds are reduced to molecular nitrogen (N2
> and nitrous oxide (NzO), and the organic carbon is decomposed to become carbon dioxide (CO2), which is released outside of the septic tank A.

In this way, the decomposition treatment of organic matter in the first chamber a1,
This can be reduced as much as possible not only by anaerobic treatment but also by partial return water from the aerobic treatment room a and the denitrifying bacteria that act on it.

In this way, the treated water that has undergone aerobic decomposition bypasses the lower part of the partition wall 3, flows into the lower part of the sedimentation separation chamber a, and rises while precipitating extremely small amounts of solid matter remaining in the treated water. Then, the solid disinfectant flows into the disinfection chamber l8 and is sterilized by the solid disinfectant that gradually flows out from the medicine cylinder 18b.
7 to the downstream side of the treated water discharge pipe.

In addition, by making the sedimentation separation chamber a4 an upflow type, the sludge blanket grows and can collect even small flocs with relatively light specific gravity, and the inner bottom of the sedimentation separation chamber a is made aerobic. It descends steeply in the direction of treatment chamber a.
I am trying to move it to the bottom of 3.

In this way, the final treated water that is purified from the toilets, kitchens, etc. of the home and discharged to the downstream side of the treated water drainage pipe is treated in the aerobic treatment room a. Since some of the water is refluxed, BOD and nitrogen concentrations can be significantly reduced. can also be done.

Therefore, excessive increase in ammonia nitrogen (NH4 -N) produced when performing anaerobic treatment only with anaerobic bacteria (
This suppresses the activity of anaerobic bacteria, which works in the direction of suppressing the activity of anaerobic bacteria, and by this suppressing effect, the activity of anaerobic bacteria can be maintained at a suitable state at all times. The decomposition treatment of organic matter can be dramatically improved.

In addition, by improving the ability to decompose organic matter, it is possible to significantly reduce the amount of untreated organic matter contained in the treated water transferred from the anaerobic treatment chamber C to the aerobic treatment chamber A. The generation of sludge in the aerobic treatment chamber a3 caused by @ substances can also be reduced as much as possible.

On the other hand, nitrate nitrogen (Noffi--N) and nitrite nitrogen (Noffi--N) in the treated water in the aerobic treatment room a3
), some of the treated water is returned to the anaerobic treatment chamber C, and those ions are converted to molecular nitrogen (N2) by denitrifying bacteria.
It can be decomposed into nitrous oxide (NZO) and nitrous oxide (NZO).

According to experiments conducted by the present applicant, the BOD concentration etc. in the final treated water obtained by the septic tank A according to this example were as shown in the table below.

Note that the numerical values are expressed as average values.

Unit (mg/1)? As is clear from the above table, in the case of this example, the BOD concentration etc. can be significantly reduced compared to the conventional septic tank.

Also, the amount of wastewater flowing into the anaerobic treatment room C is Q! , the partial recirculation amount from aerobic treatment chamber a3 to anaerobic treatment chamber C is ll
12, the amount 03 of treated water transferred from the anaerobic treatment chamber C to the aerobic treatment chamber a3 is Q3-0■+0■, but 0. 20Z=l: 1-10 (optimally 1-2-6
It was found that it is preferable to

Furthermore, as described above, in this embodiment, by controlling the pump driving device M2 of the pump P for partial reflux by the inverter 60, the amount of partially refluxed aerobic treated water to the aerobic treatment chamber C is slightly reduced. Can be adjusted, septic tank body a
The purification capacity of septic tank A is always maintained at an optimal state regardless of fluctuations in the temperature of the treated water inside, the ambient temperature (air temperature) around septic tank body A, and the inflow load (quantity, quality) into septic tank body A. be able to.

(f) Effects As explained above, the present invention has the following effects.

In other words, by finely adjusting the amount of aerobic treated water that is partially returned from the aerobic treatment chamber to the anaerobic treatment chamber, the water temperature of the treated water in the septic tank body a and the atmospheric temperature (air temperature) around the septic tank body a can be adjusted. 〉, inflow load (quantity, quality) into the septic tank body a
Regardless of changes in environmental conditions such as, the purification capacity of the septic tank is kept in the optimal state 23 14F vertical reflux pipe 14b: return pipe 50: II! Air volume control valve 60: Inverter

Claims (1)

[Claims] 1. An anaerobic treatment chamber (C) and an aerobic treatment chamber (a_3) are arranged side by side in the septic tank body (a), and aeration is carried out in the aerobic treatment chamber (a_3). Along with arranging the device (13),
Part of the treated water in the aerobic treatment chamber (a_3) can be returned, and the amount of part of the treated water returned can be finely adjusted using the inverter-controlled part return pump (P). A septic tank that can adjust the flow rate from the aerobic treatment chamber to the anaerobic treatment chamber. 2. The method according to claim 1, wherein the amount of partially recycled treated water is finely adjusted according to changes in the temperature of the treated water in the septic tank, the ambient temperature around the septic tank, and the inflow load to the septic tank. A septic tank that can adjust the flow rate from the aerobic treatment room to the anaerobic treatment room.